215 
O'Brien. — The Proteids of Wheat . 
The aleuron-layer comes into close relationship with the 
embryo in two ways: (i) Its cells are continued over the 
external surface of the edge of the scutellum where it reaches 
the convex side of the grain ; and here the aleuron-cells of 
the two seem continuous. This fact is the more noticeable 
because the cells of the scutellum bordering on the endosperm 
proper are glandular, whilst those forming its boundary 
towards the plumule are cuticularised. The aleuron-layer 
seems also to be continued over the rest of the embryo 
externally. (3) Beneath the well-marked furrow of the grain 
of Wheat the aleuron-cells pass inwards, the layer from one 
side meeting that from the other, both then sinking for some 
way into the endosperm proper. Thus, towards the base of 
the seed, they come into direct contact with the glandular 
face of the scutellum. Hence, the ‘ ringing ’ experiments in 
which it is attempted to destroy the connexion between 
embryo and aleuron-layer by an incision round the margin 
of the scutellum are not decisive, the second means of possible 
communication remaining intact. 
The A leuron- Cells . — Each cell of the aleuron-layer is 
polygonal in outline in surface view, with walls normal to 
the surface of the seed. Its protoplasm is continuous with 
that of adjoining aleuron-cells and that of the underlying 
endosperm ; it encloses a large nucleus, and forms a firm close 
network embracing the aleuron-grains. Much oil is present, 
and perhaps some carbohydrate ; this seems the explanation 
of the effect of the addition of concentrated sulphuric acid — 
the protoplasm being immediately fixed and assuming a deep 
rosy tint. (Cf. the black colour observed by Schenk on 
addition of strong sulphuric acid.) 
The Aleur on- Grains . — Each aleuron-grain, as observed on 
the first addition of water or glycerine, or in oil or almost 
any mounting medium, is seen to be a spherical or somewhat 
angular body. It is seen also to consist of a central core 
surrounded by an outer layer. The core is a refracting body, 
more or less soluble in water, salt-solutions, dilute acids, and 
alkalies ; it does not readily stain. The outer layer, on the 
